Thread tension devices for sewing machines



Jan. 14, 1969 N. E. ZACHER THREAD TENSION DEVICES FOR SEWING MACHINES Sheet Filed June 8, 1965 I NVEN TOR. Norman E. Zacher Q4 62.1. Jim/v5) Jan. 14, 1969 N. E. ZACHER THREAD TENSION DEVICES FOR SEWING MACHINES Sheet 2 Filed June 8. 1965 ATTORNEY United States Patent 3,421,713 THREAD TENSION DEVICES FOR SEWING MACHINES Norman E. Zacher, Livingston, N.J., assignor to The Singer Company, New York, N.Y., a corporation of New Jersey Filed June 8, 1965, Ser. No. 462,253

US. Cl. 242-155 Int. Cl. B6511 59/18 ABSTRACT OF THE DISCLOSURE A thread tension device comprising primary means including a thread pulley carried at one end of a rotatably mounted shaft and carrying at its other end a drag drum having a braking spring operatively associated therewith for controlling the tension in the thread, and secondary means including a check spring also for controlling the tension in the same thread operatively connected to the brake spring so that the effect of the check spring on the tension of the thread automatically will be regulated as the tension placed on the thread by the primary means is regulated by movement of an adjusting lever.

Summary This invention relates to thread tension devices and more particularly to improved thread tension devices especially adapted, though not necessarily restricted, to being mounted on the bracket-arm head of a family type sewing machine.

Many different types of tension devices have been designed and used in the past for applying tension to a thread, but previously used devices have not always tensioned the thread as accurately as desirable. Furthermore, it has not always been possible to move the setting of conventional tension devices from a first tension setting, to a second tension setting and then back to the first or original setting and to thereby develop exactly the same tension on the thread after the device has been reset as was developed in the first instance. Also previously known tension devices have been equipped with so called check springs which operated entirely independently of the main tension setting. Because of this, the effect of the check spring did not vary as the main tension of the device was set and reset, and therefore, if previously used check springs were set to function properly when the main tension device was set for a relatively low tension, they did not function properly when the main tension device was set for a relatively high tension and vice versa. Therefore, an important object of the present invention is to provide an improved thread tension device.

Another object of the invention is to provide an improved thread tension device having facilities for very accurate control of the tension applied to the thread.

A further object of the invention is to provide an improved thread tension device in which any particular setting of the thread tension adjusting lever always provide the same tension on the thread.

A still further object of the invention is to provide an improved thread tension device which is so constructed and arranged that increasing the tension applied to the thread automatically increases the effect of the check wire or check arm on the thread.

With the above and other objects in view, as will hereinafter appear, the invention comprises the devices, combinations and arrangements of parts hereinafter set forth and illustrated in the accompanying drawings of a preferred embodiment of the invention, from which the several features of the invention and the advantages at- Claims ice tained thereby will be readily understood by those skilled in the art.

Brief description of the drawings In the accompanying drawings:

FIG. 1 is a front elevational view of a preferred form of thread tension device embodying the present invention.

FIG. 2 is a side elevational view of the device shown in FIG. 1, parts having been broken away,

FIG. 3 is a rear elevational view of the device shown in FIGS. 1 and 2,

FIG. 4 is an exploded perspective view showing parts of the thread tension device shown in FIGS. 1 through 3,

FIG. 5 is a front elevational view of a second form of thread tension device embodying the present invention,

FIG. 6 is a side elevational view (partly in section) of the device shown in FIG. 5,

FIG. 7 is a rear elevational view of the device shown in FIGS. 5 and 6, and

FIG. 8 is an exploded perspective view showing parts of the thread tension device illustrated in FIGS. 5 through 7.

Description of the preferred embodiments In the embodiment of the invention illustrated in FIGS. 1 through 4, the numeral 16 indicates a preferred form of thread tension device mounted on a plate 17 which may be secured to the head of a sewing machine similar to the sewing machine head shown in US. Patent No. 3,150,846 or if desired the head of the sewing machine may be modified to take the place of the plate 17 and in this instance the thread tension device 16 would become an integral part of the head of the sewing machine.

Specifically the embodiment of the invention illustrated in FIGS. 1 through 4, forming a part of this specification, comprises the previously mentioned mounting plate 17 which is provided with holes 21, 22, 23, 24, 25 and 26. The hole 21 receives one end of an arm of a forwardly extending L-shaped thread guide 31. The holes 22 and 23 receive the ends of forwardly projecting thread guides 32 and 33. The hole 24 neceives the end of a check arm shaft later to be described, and the hole 25 receives the shank of a screw 35. The hole 26 receives a bearing bushing 36, and the for-ward or front portion of the plate 17 is formed with a counterbore 37 concentric with the hole 26. Also the rear portion of the plate 17 is provided with an integrally formed rearwardly projecting boss 38 which is also concentric with the hole 26.

The bearing bushing 36 rotatably supports a solid cylindrical drive shaft 46 which at its forward end is formed integral with a circular head 51.

The shaft 46, toward its rearward end, has rotatably mounted thereon a drag drum 53 formed with a circumferentially extending V-shaped groove 56, the function of which will presently be described. The shaft 46 adjacent to the head 51 carries a cylindrically shaped thread pulley 62 having two V-shaped thread receiving grooves 73 and 74 and a counterbore 77 for receiving the head 51 of the shaft 46. Also the rearward side of the pulley 62 has a hub 69 formed integral with the pulley 62, the hub 69 riding against one end of the bearing bushing 36 which thus acts as a thrust hearing.

The hereinbefore mentioned boss 38 of the plate 17 turnably supports, by means of an aperture 81, one end of a tension adjusting lever 82, the free end of which is in the form of a forwardly extending hook or tension indicator 83. Intermediate the aperture 81 and the indicator 83, the lever 82 carries an apertured creep spring anchor 84 to which is connected one end of a helical creep spring 86. The other end of the creep spring 86 is hooked to a reach of a substantially S-shaped check wire or arm 89. One end of the check arm 89 is secured in a substantially tangent relationship to a sleeve 80 which is turnably mounted on a post 85 one end of which is fixed into the previously mentioned hole 24 in the plate 17. The free end of the check arm 89 is formed into a thread eyelet 91. The check arm stop 92 is, by reason of its slot 93, adjustably held to the plate 17 by the screw 35.

The end of the shaft 46 rotatably carries a washer 90 which has a small diameter portion 94 for receiving one end of a helical compression spring 95, the other end of the spring 95 abutting against a side face of the drag drum 53. The washer 90 is prevented from slipping off the end of the shaft 46 by reason of the shaft 46 being upset as at 96 after the parts have been assembled. The shaft 46 intermediate its portions 51 and 96 is formed with a slabbed portion 97 which acts as one part of a coupling clutch, the other part of the coupling clutch being a noncircular indentation 98 formed in the face of the drag drum 53.

The above described thread tension device, (FIGS. 1 through 4) functions in the following manner. Two thread grooves are provided so that, regardless of where the thread (indicated by a dash-dot line in FIG. 1) is inserted in the device, it will enter one of the grooves and the thread is wrapped one and one-half times around the base of the groove 73 or 74 as the case may be. As the thread is drawn from a supply spool (not shown) to work (not shown), the wrap of the thread around the base of either the groove 73 or 74 causes the pulley 62 to rotate. Rotation of the pulley 62, which is fixed to the shaft 46, drives the drag drum 53 by reason of the slabbed portion 97 on the shaft 46 clutching the non-circular indentations 98 in the drag drum 53, it being understood that the compression spring 95 presses the non-circular indentations 98 into engagement with the slabbed portion 97. The spring 86, which rides in the groove 56 of the drag drum 53, resists or brakes rotation of the drum 53, the shaft 46 and the thread pulley -62. Effectiveness of the braking action of the spring 86 on the drum 53 can be adjusted by turning the tension adjusting lever 82 to any desired position between the low drag position shown in solid lines and the high drag position shown in dash-dash lines FIGS. 1 and 3. Also the effectiveness of the braking action of the spring 86 on the drum 53 is automatically regulated by the turning of the sleeve 80 as governed by the position of the check arm 89. If the tension in the thread should increase, the check arm 89 and the sleeve 80 will turn (clock-wise as shown in FIG. 1 or counterclockwise as shown in FIG. 3) to increase the tension of the spring 86 and thus increase the braking or drag on the drum 53. The resistance to movement of the check arm 89 is directly proportioned to the setting of the indicator 83. Thus, for decreasing tension setting of the indicator 83, the check arm 89 becomes lighter.

Complete tension release is achieved by moving the drive shaft 46 endwise (left to right as seen in FIG. 2). This disengages the clutch part of slabbed portion 97 from engagement with the other clutch part or non-circular indentation 98 in the drag drum 53. When pressure on the end of the shaft 46 is released, the spring 95 reengages the clutch parts 97 and 98. When the clutch parts are disengaged, the pulley 62 will turn freely.

In the embodiment of the invention illustrated in the FIGS. through 8 numeral 116 indicates a second form of thread tension device mounted on a plate 117 which may be secured to the head of a sewing machine similar to the sewing machine head shown in US. Patent No. 3,150,846 or, if desired, the head of the sewing machine may be modified to take the place of the plate 117 and in this instance the thread tension device 116 would become an integral part of the head of the sewing machine.

Specifically the embodiment of the invention illustrated in the drawings, forming a part of this specification, comprises the previously mentioned mounting plate 117 which is provided with holes 121, 122, 123, 124, and 126. Hole 121 receives one end of an arm of a forwardly extending L-shaped thread guide 131. Holes 122 and 123 receive the ends of forwardly projecting thread guides 132 and 133. The hole 124 receives the stem of a flanged bushing 134, and the hole 125 is internally threaded and thereby receives the threaded end of the screw 135. The hole 126 receives a bearing bushing 136 and the forward or front portion of the plate 117 is formed with a counterbore 137 concentric with the hole 126. Also the rear portion of the plate 117 is provided with an integrally formed rearwardly projecting sleeve 138 which is also concentric with the hole 126.

The bearing bushing 136 rotatably supports a cylindrical or outer drive shaft 139 which at its forward end is formed integral with an annular clutch plate 141 the forward face of which has glued thereto a clutch facing 142. The rearward end of the shaft 139 carries a frustoconical half-drag drum 143. The aperture 144 in the cylindrical drive shaft 139 rotatably supports a solid cylindrical or inner drive shaft 146 which at its forward end is formed integral with a circular clutch plate 151, the rearward face of which has glued thereto a clutch facing 152. The rearward end of the shaft 146 carries a frustoconical halfdrag drum 153, the two drag drums 143 and 153 being so positioned that their smaller diameter faces are positioned adjacent to one another, thereby providing between the two drums 143 and 153 a substantially V-shaped groove 156, the function of which will presently be described.

The shaft 146 between the clutch facings 142 and 152 carries in the following order, starting from the clutch facing 142, a thread-pulley 162, a thread-disc 163, a plastic washer 164, a second thread disc 166, and a second thread pulley 167. The thread pulley 162 is apertured as at 168 and thereby receives a hub portion 169 of the disc 163. In like manner the thread pulley 167 is apertured as at 171 and thereby receives a hub portion 172 of the disc 166. The forward face of the pulley 162 and the rearward face of the thread disc 163 are frustoconical and cooperate to form an annular V-shaped thread receiving groove 173. Also the forward face of the thread-disc 166 and the rearward face of the pulley 167 are frustoconical and cooperate to form a second annular V-shaped thread receiving groove 174.

The hereinbefore mentioned sleeve 138 of the plate 117 turnably supports, by means of an aperture 181, one end of a tension adjusting lever 182, the free end of which is in the form of a forwardly extending hook or tension indicator 183. Intermediate the aperture 181 and the indicator 183, the lever 182 carries an apertured creep spring anchor 183 to which is connected one end of a helical creep spring 186. The other end of the creep spring 186 is hooked into a diametrical hole 187 formed in one end of a shaft 188 turnably supported by the bushing 134. A substantially S-shaped check wire or arm 189 extends from the front end of the shaft 188 and the free end of the arm 189 is formed into a thread eyelet 191. A check arm stop 192 is, by reason of its slotted hole 193, adjustably held to the plate 117 by the screw 135.

From the above it will be understood that:

(a) The half drag drum 153 is secured to one end of the drive shaft 146, and on the other end of the drive shaft 146 there is mounted the clutch plate 151. Thus the drum 153 is driven by the plate 151 by way of the shaft 146.

(b) The half drag drum 143 is secured to one end of the drive shaft 139, and on the other end of the shaft 139 there is mounted the clutch plate 141. Thus the drum 143 is driven by the plate 141 by way of the shaft 139.

(c) The drive shaft 139 is turnably mounted in the bushing 136.

(d) The shaft 146 is turnably mounted in the shaft 139.

(e) The thread disc 163 is freely rotatable on the shaft 146.

(f) The thread pulley 162 is secured to the hub 169 formed on the thread disc 163, thus the pulley 162 and the disc 163 rotate together when driven by a thread in the groove 173.

(g) The thread disc 166 is freely rotatable on the shaft 146.

(h) The thread pulley is secured to a hub 172 formed on the thread disc 166. Thus the pulley 167 and the disc 166 rotate together when driven by a thread in the groove 174.

(i) The clutch facing 142 is secured to the clutch plate 141.

(j) The clutch facing 152 is secured to the clutch plate 151.

(k) The spring 186 is positioned in the groove 156 and thus engages both drag drums 143 and 153.

The above described thread tension device (shown in FIGS. 5 through 8) functions in the following manner. Two threads (indicated by a dash-dot line in FIG. 5) are tensioned at the same time. One thread makes a one and one-half wrap around the base of the groove 173 formed by the pulley 162 and the disc 163. The other thread makes a one and one-half wrap around the base of the groove 174 formed by the pulley 167 and the disc 166.

As either one or both of the threads are drawn from supply spools (not shown) to the work (not shown), the wraps of the threads around the bases of the grooves 173 and 174 respectively cause the thread pulleys 162 and 16-7 to rotate and respectively engage the clutch facings 142 and 152. Rotation of the pulley 162 by way of the clutch facing 142 causes the clutch plate 141, the shaft 139, and the half drag drum 143 to rotate. In like manner, rotation of the pulley 167 by way of the clutch facing 152 causes the clutch plate 151 the shaft 146, and the half drag drum 153 to rotate. The spring 186 in the groove 156 causes the drums 143 and 153 to separate and thus cause the clutch facings 142 and 152 to engage respectively the thread discs 162 and 1-67, and the spring 186, by reason of engaging the drag drums 153 and 143 resists or brakes rotation of the drums 153-143, the shafts 146-139 and the clutch plates 151-141. Effectiveness of the braking action of the spring 186 on the drums 143-153 can be adjusted by turning the tension adjusting lever 182 to any position between the low drag position shown in solid lines, and the high drag position shown in dashdash lines in FIGS. 5 and 7. Also the effectiveness of the braking action of the spring 186 on the drums 143-153 is automatically regulated by the turning of the shaft 188 as governed by the position of the check arm 189. If the tension in the thread should increase, the check arm 189 and shaft 188 will turn (clockwise as shown in FIG. 5 or counterclockwise as shown in FIG. 7) to increase the tension of the spring 186 and thus increase the braking or drag on the drums 143-153. The resistance to movement of the check arm 189 is directly proportioned to the setting of the indicator 183. Thus, for decreasing tension setting of the indicator 183, the check arm 189 becomes lighter.

Complete tension release is achieved by moving the inner drive shaft 146 endwise (left to right FIG. 6). This disengages the clutch facings 142 and 152 from their respective pulleys 162 and 167 and allows the pulleys to rotate freely Without drag. When pressure on the end of the shaft 146 is release-d, the spring 186 causes the clutch facings 142-152 to reengage with the pulleys 162- 167.

Having thus described the nature of the invention, what I claim herein is:

1. A thread tension device comprising in combination, a primary means for controlling the tension in a thread, an adjusting device for changing the effect of the primary means on the tension of the thread, means for turnably supporting said adjusting device with said primary means for effecting the change in thread tension, a secondary means for controlling the tension in the same thread, said secondary means comprising a check arm having an eyelet through which the thread passes, and means for operatively connecting said primary means and said secondary means to regulate the effect of the secondary means on the thread simultaneously as the effect of said primary means on the tension of the thread is adjusted by way of said adjusting device.

2. A tension device comprising a shaft, means for rotatably mounting said shaft, a thread pulley mounted on said shaft for continuous operative engagement therewith in all directions of rotary shaft movement, a drag drum mounted on said shaft, means operatively engaging said drag drum for braking rotation of said drag drum, and clutch means for connecting and disconnecting said thread pulley to said drag drum.

3. A tension device comprising in combination a mounting plate, a shaft rotatably supported by said bearing means, a thread pulley on said shaft, a drag drum rotatably carried by said shaft, clutch means so constructed and arranged as to connect and disconnect said thread pulley and drag drum, a tension adjusting lever, means for operably connecting said lever to said mounting plate, a creep spring engaging said drag drum, and means for connecting said creep spring to said tension adjusting lever such that movement of said lever varies the effect of the creep spring on the drag drum, whereby thread tension of the pulley is altered.

4. A tension device comprising in combination a mounting plate, bearing means carried by said mounting plate, a shaft rotatably supported by said bearing means, a thread pulley on said shaft, a drag drum rotatably carried by said shaft, clutch means so constructed and arranged as to connect and disconnect said thread pulley and said drag drum, a check arm, a tension adjusting lever, means for operably connecting said adjusting lever to said mounting plate, further means for operably supporting said check arm on said adjusting lever, a creep spring engaging said drag drum, means for connecting said creep spring to said adjusting lever, and means for connecting said creep spring to said check arm, whereby movement of said lever varies the effect of the creep spring on the drag drum to thereby vary tension on the check arm and on the thread on the pulley.

5. A tension device comprising in combination a mounting plate, bearing means carried by said mounting plate, a shaft rotatably supported by said bearing means, a thread pulley fixed to one end of said shaft, a drag drum rotatably carried by the other end of said shaft, clutch means so constructed and arranged as to connect and disconnect said thread pulley and said drag drum, a substantial S-shaped check arm mounted to turn with respect to said mounting plate, a hooked tension adjusting lever adjustably mounted with respect to said mounting plate, a helical creep spring engaging said drag drum, means for connecting one end of said creep spring to said adjusting lever, and means for connecting the other end of said creep spring to said check arm, whereby movement of the lever varies the drag of the spring on the drum to vary the tension on the check arm and that of the pulley.

6. A tension device comprising in combination a mounting plate, bearing means carried by said mounting plate, a cylindrical hollow drive shaft rotatably mounted in said bearing means, a first half drag-drum secured to said hollow shaft, a first clutch plate secured to said 1101- low shaft, an inner drive shaft rotatably mounted in said hollow drive shaft, a second half drag-drum secured to said solid drive shaft, a second clutch plate secured to said inner shaft, a first thread pulley rotatably mounted on one of said shafts adjacent to one of said clutch plates, a second thread pulley rotatably mounted on one of said shafts adjacent to the other of said clutch plates, a tension adjusting lever mounted on said mounting plate, a spring so constructed and arranged as to engage both of said half drag-drums and means for conecting said spring to said tension adjusting lever, whereby movement of the lever varies the drag of the spring on the drum to vary the tension of the thread pulley.

7. A tension device comprising in combination a mounting plate, bearing means carried by said mounting plate, a cylindrical hollow drive shaft rotatably mounted in said bearing means, a first half drag-drum secured to said hollow shaft, a first clutch plate secured to said hollow shaft, an inner drive shaft rotatably mounted in said hollow drive shaft, a second half drag-drum secured to said inner drive shaft, a second clutch plate secured to said inner shaft, a first thread pulley rotatably mounted on one of said shafts adjacent to one of said clutch plates, a second thread pulley rotatably mounted on one of said shafts adjacent to the other of said clutch plates, a tension adjusting lever mounted on said mounting plate, a check arm mounted to turn with respect to said mounting plate, a spring so constructed and arranged as to engage both of said half drag-drums, means for connecting said spring to said tension adjusting lever, and means for connecting said spring to said check arm, whereby movement of the lever varies the drag of the spring on the drum to vary tension on the check arm and that of the thread pulley.

8. A tension device comprising in combination a mounting plate, bearing means carried by said mounting plate, a cylindrical hollow drive shaft rotatably mounted in said bearing means, a first half drag-drum secured to one end of said hollow shaft, a first clutch plate secured to the other end of said hollow shaft, an inner drive shaft rotatably mounted in said hollow drive shaft, a second half drag-drum secured to one end of said inner drive shaft,

a second clutch plate secured to the other end of said inner shaft, a first thread pulley rotatably mounted on said inner shaft adjacent to said first clutch plate, a second thread pulley rotatably mounted on said inner shaft adjacent to said clutch plates, a tension adjusting lever turnably mounted on said mounting plate, a substantially S-shaped check arm mounted to turn with respect to said mounting plate, a helical creep spring so constructed and arranged as to engage both of said half drag-drums, means for connecting one end of said creep spring to said tension adjusting lever, and means for connecting the other end of said creep spring to said check arm, whereby movement of the lever varies the drag of the spring on the drum to vary tension on the check arm and that of the thread pulley.

9. A tension device according to claim 3, wherein the creep spring is helical in configuration.

References Cited UNITED STATES PATENTS 668,070 2/1901 Van Patten 242- 686,014 11/1901 Webster 242-450 2,574,378 11/1951 Crookston 242-155 2,580,077 12/ 1 Deihle 242155 XR 2,640,663 6/1953 Leland 242155 3,327,964 6/ 1967 Nvussbaumer 242--155 JORDAN FRANKLIN, Primary Examiner.

G. H. KRIZMANICH, Assistant Examiner. 

